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Cell Syst. 2017 Dec 27;5(6):578-590.e6. doi: 10.1016/j.cels.2017.11.005. Epub 2017 Dec 1.

Homeostatic Cell Growth Is Accomplished Mechanically through Membrane Tension Inhibition of Cell-Wall Synthesis.

Author information

1
Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
2
Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA. Electronic address: kchuang@stanford.edu.
3
Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: theriot@stanford.edu.

Abstract

Feedback mechanisms are required to coordinate balanced synthesis of subcellular components during cell growth. However, these coordination mechanisms are not apparent at steady state. Here, we elucidate the interdependence of cell growth, membrane tension, and cell-wall synthesis by observing their rapid re-coordination after osmotic shocks in Gram-positive bacteria. Single-cell experiments and mathematical modeling demonstrate that mechanical forces dually regulate cell growth: while turgor pressure produces mechanical stress within the cell wall that promotes its expansion through wall synthesis, membrane tension induces growth arrest by inhibiting wall synthesis. Tension inhibition occurs concurrently with membrane depolarization, and depolarization arrested growth independently of shock, indicating that electrical signals implement the negative feedback characteristic of homeostasis. Thus, competing influences of membrane tension and cell-wall mechanical stress on growth allow cells to rapidly correct for mismatches between membrane and wall synthesis rates, ensuring balanced growth.

KEYWORDS:

homeostasis; mathematical modeling; membrane potential; osmotic stress; peptidoglycan; turgor pressure

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